Hospital beds typically comprise a frame extending longitudinally from a head end to a foot end and laterally from a left side to a right side, and a deck affixed to the frame. The deck may be a segmented deck having one or more sections whose angular orientation is adjustable by pivoting the deck section about a laterally extending axis. For example the deck may have a torso section positionable between angular orientations of 0° to 65° relative to the frame. A mattress rests on the deck. The mattress may be constructed of foam, inflatable bladders or a combination of foam and inflatable bladders and exhibits enough flexibility to conform to the profile defined by the orientation adjustable deck sections. The bed may also include a pair of turn assist bladders, one on each side of the longitudinal centerline of the bed. The turn assist bladders are deflated when not in use.
A bed occupant or a caregiver may operate the bed to change the angular orientation of one of the adjustable deck sections and the corresponding portion of the mattress. In addition, the caregiver may inflate one or the other of the turn assist bladders to tilt the occupant to the left or right thereby assisting in efforts to turn the occupant from, for example, a prone position to a supine position. The caregiver may also use the turn assist bladders to apply various therapeutic or preventive treatments. One example of such a treatment is Continuous Lateral Rotation Therapy (CLRT). CLRT involves slowly inflating and deflating the turn assist bladders out of phase with each other in order to gently turn the bed occupant alternately to the left and right by about 20°-45° in each direction. The alternate turning helps resist fluid accumulation in the occupant's lungs, mobilizes secretions already present in the lungs, and increases aeration of the lungs. Another example treatment is Lateral Pressure Relief (LPR) which involves a similar left to right cycling of about 10° to guard against the onset of decubitus ulcers.
Experimental evidence suggests that turn assist, CLRT and LPR are most effective if the occupant is laterally centered on the mattress and lying substantially parallel to the longitudinal direction before inflation of the underlying turn assist bladder begins. Otherwise inflation of the turn assist bladder may simply elevate the occupant rather than turn or tilt him. Accordingly, it is desirable to develop systems and methods for prepositioning a mispositioned occupant, particularly in the lateral direction, prior to initiating turn assist, CLRT, LPR or other lateral rotations. Such systems and methods may also be useful in prepositioning an occupant, particularly in the longitudinal direction, prior to changing the orientation of the orientation adjustable deck sections, such as the torso section.